Due to overlaying intelligent networks over common-used circuit switching networks, not only can we make common calls, but also we can get other intelligent services through dialing different Service Access Codes. At present, widely-used intelligent network services include Freephone, Account card calling (ACC), Virtual private network (VPN), Universal Personal Telecommunication (UPT), Wide Area Centrex (WAC), Televoting (VOT) and Mass Calling (MAS) Service and so on.
U.S. Pat. No. 5,479,495 (Method and system for automatically accessing and invoking switch-based services in an advanced intelligent network) and U.S. Pat. No. 5,553,130 (Number translation services matrix) disclose the ways for implementing PSTN-based services of providing SCP, their contents are incorporated herein by reference.
In the next generation communication networks, there will be much more intelligent service providers providing services, so it is necessary to continue such intelligent network services in the next generation networks. On the other hand, traditional intelligent network services can not be replaced at one night, as a result, the following requirements arise: the users of the traditional PSTN network want to access intelligent networks in the next generation networks and the users in the next generation networks want to access the intelligent services in the traditional PSTN networks. In other words, there is a need of interconnection of intelligent network services between PSTN networks and the next generation networks.
However, because of the essential differences in structures, principles and standards between traditional PSTN networks and the next generation networks, it is very difficult to realize the requirements mentioned above.